Astronomers find most distant member of the solar system

When most people think about the solar system, they consider the Sun, the eight planets, and Pluto.

But although space is, indeed, mostly empty the solar system is a rather complex place. And today scientists have announced the discovery of a second, mysterious object far, far away from the Sun but still in orbit around our star.

The object does not yet have a name — for now it’s 2012 VP113 — and it’s a lot like Sedna, which was found in 2003.

According to a research paper published in Nature today, this object is estimated to be about 280 miles across, or about the distance from Galveston to Dallas. At such a size it would likely be considered a dwarf planet, in the same category as Pluto. Sedna is about twice as large.

But the orbit of this object is anything but Pluto-like, and it’s discovery is helping astronomers to better understand what conditions are like at the edge of our solar system.

To put this discovery let us first take a look at the solar system.

Our solar system, not to scale. (NASA)

In the graphic above the scale bar is in astronomical units, with each set distance beyond 1 AU representing 10 times the previous distance. One AU is the distance from the sun to the Earth, which is about 93 million miles or 150 million kilometers. Neptune, the most distant planet from the sun, is about 30 AU. Pluto’s orbit fluctuates between 30 AU and 50 AU from the Sun.

The new objects, like Sedna and 2012 VP113, have much more eccentric orbits. Sedna, for example, makes its closest approach at 76 AU, but at the most distant part of its orbit is nearly 1,000 AU from the Sun. The new object, 2012 VP113, comes within 80 AU of the Sun at perihelion.

To understand how eccentric these orbits are here’s the orbit of Sedna compared to that of the other planets and Pluto (in purple) in our solar system.

The orbit of Sedna (red) set against the orbits of Jupiter (orange), Saturn (yellow), Uranus (green), Neptune (blue), and Pluto (purple). (Wikimedia)

Astronomers believe both Sedna and the new object are members of a population of “inner Oort cloud” objects, and that there are likely many other of these tiny worlds.

Here’s one more image showing both Sedna (orange), the new object, and the rest of the solar system,

The distant objects not only are fascinating in and of themselves — what are they? rocky? ice balls? where Katy evacuated to?– their existence, and their nature, will help astronomers further pin down how the solar system formed.